The instant invention relates to envelope inserting apparatus, and more particularly to apparatus for guiding the envelope to the inserting station.
Envelope stuffing machines, for example of the type shown in U.S. Pat. No. 2,736,999 issued Mar. 6, 1956 to F. J. Rouan, et al., U.S. Pat. No. 2,914,895 issued Dec. 1, 1959 to S. W. Martin, U.S. Pat. No. 4,077,181 issued Mar. 7, 1978 to L. K. Asher, et al., and U.S. Pat. No. 4,169,341 issued Oct. 2, 1979 to F. T. Roetter, et al., all of which patents are assigned to the assignee of the present invention, generally include: structure for delivering an envelope, with its address panel oriented upwardly and its flap opened, to a registration gate at an enclosure inserting station; structure for timely opening the delivered envelope, including a plurality of fingers known in the art as stripper fingers, which are insertable into the throat of the envelope for opening the same; and structure for inserting an enclosure into the opened envelope. More particularly, the envelope opening structure of these devices includes a plate which acts as a ledge upon which the flap of the envelope is located when it is delivered to the inserting station.
In U.S. Pat. No. 4,337,609 issued Jul. 6, 1982 to D. H. Foster, et al. and assigned to the assignee of the present invention, there is shown an envelope stuffing apparatus which includes an enclosure ram, a pair of outfeed push rollers and stripper fingers. The ram comprises a reciprocal ram plate having a depending portion which engages the enclosures. On the forward stroke of the ram plate, the plate carries therewith the enclosures into the throat of the opened envelope. As is well known in the art, the ram plate also moves the stuffed envelope downstream into feeding engagement with the outfeed rollers. Accordingly, the ram and outfeed rollers cooperate with each other for removing stuffed envelopes from the insert station.
The ram envelope stuffing apparatus of the above type has been successfully employed for many years. Although working well, there is a limitation on the throughput at the insertion station because of the reciprocating action of the ram plate. Typically, the ram insertion station operates well at a rate less than 6000 cycles (or envelopes per hour) for #10 (4 inch by 9 inch) envelopes. The rate of operation varies for different sized envelopes.
Improvements have been made recently in the throughput of the upstream modules of the inserter machine. However, the insert station employing the ram plate cannot take advantage of the improvements to the throughput of the upstream modules. This is, in part, due to the physical constraints associated with the ram mechanism, and, in part, to the motion lo inherent in the operating ram. Attempts at increasing the throughput of the ram type insert station has resulted in severe vibrations as the mass of the ram reciprocates at higher speeds. Such vibrations induce severe life shortage of the parts in the insert station. In addition, the reliability of the insert station decreases significantly at the higher speeds.
Accordingly, U.S. Pat. No. 5,255,498, issued Oct. 26, 1993 to the assignee of the instant invention, provided pusher fingers to replace the ram mechanism. The pusher fingers allow the insert station throughput speed to be increased without the problem inherent with increasing the speed of the ram mechanism. The '498 patent also provided a replacement for the typical fingers or envelope throat openers. The replacement comprises a throat opener having a side guide for preventing the enclosures from crashing into the side of the envelope.
The approach of the '498 patent did in fact allow higher operating speeds. However, such speeds had a limit, so that the inserting process was limited to about 10,000 cycles (or envelopes) per hour. Increasing the speed of the insertion process above 10,000 cycles per hour resulted in envelopes bouncing back from the envelope stops and not being in proper position for insertion, thereby resulting in jams.
Thus, the instant invention provides apparatus which prevents the envelope from bouncing back from the envelope stops at the insert station, thereby allowing the entire insertion process to be run at speeds of 13,000 cycles per hour and higher.